diff --git a/docs/guides/vpn/Android-Transport-Error.png b/docs/guides/vpn/Android-Transport-Error.png
new file mode 100644
index 0000000..9b38ea8
Binary files /dev/null and b/docs/guides/vpn/Android-Transport-Error.png differ
diff --git a/docs/guides/vpn/troubleshooting.md b/docs/guides/vpn/troubleshooting.md
new file mode 100644
index 0000000..bd2e640
--- /dev/null
+++ b/docs/guides/vpn/troubleshooting.md
@@ -0,0 +1,33 @@
+### CRL expired
+OpenVPN 2.4 and newer check the validity of the Certificate Revocation List (CRL). This can result in a sudden malfunction of `openvpn` after an update even though no configuration files have changed. This error manifests in the following, not very helpful, error on the client side:
+```
+Wed Apr 24 11:19:07 2019 VERIFY OK: depth=0, CN=server
+Wed Apr 24 11:19:07 2019 Connection reset, restarting [0]
+Wed Apr 24 11:19:07 2019 SIGUSR1[soft,connection-reset] received, process restarting
+Wed Apr 24 11:19:07 2019 Restart pause, 5 second(s)
+```
+Android clients simply report: "Transport error, trying to reconnect..."
+> ![](Android-Transport-Error.png)
+
+On the OpenVPN server, the following messages are logged:
+```
+Wed Apr 24 11:19:07 2019 aaa.bbb.ccc.ddd:pppp TLS: Initial packet from [AF_INET]aaa.bbb.ccc.ddd:pppp, sid=57719cb8 77945ae9
+Wed Apr 24 11:19:07 2019 aaa.bbb.ccc.ddd:pppp VERIFY ERROR: depth=0, error=CRL has expired: CN=client1
+Wed Apr 24 11:19:07 2019 aaa.bbb.ccc.ddd:pppp OpenSSL: error:11089086:SSL routines:ssl3_get_client_certificate:certificate verify failed
+Wed Apr 24 11:19:07 2019 aaa.bbb.ccc.ddd:pppp TLS_ERROR: BIO read tls_read_plaintext error
+Wed Apr 24 11:19:07 2019 aaa.bbb.ccc.ddd:pppp TLS Error: TLS object -> incoming plaintext read error
+Wed Apr 24 11:19:07 2019 aaa.bbb.ccc.ddd:pppp TLS Error: TLS handshake failed
+Wed Apr 24 11:19:07 2019 aaa.bbb.ccc.ddd:pppp Fatal TLS error (check_tls_errors_co), restarting
+Wed Apr 24 11:19:07 2019 aaa.bbb.ccc.ddd:pppp SIGUSR1[soft,tls-error] received, client-instance restarting
+```
+The error is `CRL has expired` and can be solved using the following commands:
+```
+sudo -s
+cd /etc/openvpn
+mv crl.pem crl.pem_old
+cd easy-rsa
+./easyrsa gen-crl
+cp pki/crl.pem ../
+service openvpn restart
+exit
+```
diff --git a/mkdocs.yml b/mkdocs.yml
index 67ab6ce..3bdfe7a 100644
--- a/mkdocs.yml
+++ b/mkdocs.yml
@@ -96,6 +96,7 @@ nav:
     - 'Optional: Dual operation: LAN & VPN at the same time': guides/vpn/dual-operation.md
     - 'Optional: Full and DNS-only': guides/vpn/dual-VPN.md
     - 'Optional: Dynamic DNS': guides/vpn/dynDNS.md
+    - 'Troubleshooting': guides/vpn/troubleshooting.md
   - 'TOR & Pi-hole':
           - 'Overview': guides/tor/overview.md
           - 'Basic Setup': guides/tor/setup.md